The subject of the invention is a powdered, silicone-free antifoaming agent composition for aqueous systems, especially for washing and cleaning liquors as well as a process for the preparation of the new antifoaming agent. The subject of the invention is also the use of the antifoaming agent as foam inhibitor, especially in wash and cleaning products.
The problem of regulating the suds, or foaming, in aqueous systems that tend to develop excessive foam during agitation and/or heating already resulted in numerous suggestions for its solution and led to the development of a broad state of the art. Especially with the modern washing machines, and here above all the drum washers, the control of the formation of foam in the washing liquor is indispensable over the entire washing range since excessive foaming as well as the complete absence of suds are undesirable for the washing success. An excellent antifoaming agent was found in the soaps based substantially upon C.sub.20 and C.sub.22 fatty acids, as they are available from rapeseed oil and fish oils as natural sources. However, for various reasons a reliable supply of these raw materials cannot be ensured. Also, the required relatively high concentration in which these fatty acids must be used, which is on the order of from 2% to 3.5% by weight, based on the total weight of the finished detergent, is a disadvantage.
Known silicone foam inhibitors which consist of liquid polysiloxanes with alkyl or aryl substituents and finely-divided colloidal silica, effect desired suds control with very small amounts of the inhibitor, substantially below 1% by weight, and are in this respect superior to foam-inhibiting soaps. However, the high costs of the silicone foam inhibitors and also the great number of application technology parameters which must be observed for foam control, have led to further efforts in this field to make new silicone-free antifoaming compositions available. Liquid and solid hydrocarbons or chlorinated fatty alcohols, all fatty ketones, aliphatic disulfides or sulfoxides containing up to 50 carbon atoms, and the like, partly also in combination with hydrophobic, finely-divided silicon dioxide, have been suggested as foam-inhibiting active substances. For example, a special ternary foam inhibitor consisting of a liquid paraffin, a paraffin wax or an ester wax, and a hydrophobic-reacting silicon dioxide, has become known recently from the European Published Patent Application No. 0 000 216. This ternary mixture can be incorporated in the wash product by the usual methods. This antifoaming mixture can also be present, among other physical forms, as an agglomerate with conventional powdered wash product components. A ternary antifoaming mixture consisting of a hydrophilic, nonionic dispersing agent with HLB-values of from 14 to 19 a hydrophobic-reacting silicic acid and a wax is known also from the European Published Patent Application No. 0 008 829.
This antifoaming agent intended for use in wash products is used as homogeneous dispersion that is mixed with a granulate of powdered wash product components. For this purpose, the antifoaming mixture can be changed from the heated, liquid form into a solid, finely divided form by cooling, for example, by spray-cooling, and then mixed. The spraying of the warm, liquid antifoaming dispersion onto cold tower powder or cold granulate as carrier was recommended as alterative.
The preparation of a substantially silicone-free antifoaming agent for aqueous systems is also described in our commonly-assigned U.S. patent application Ser. No. 250,683, filed Apr. 3, 1981, now U.S. Pat. No. 4,339,342. In this process, a higher molecular-weight, branched chain, primary alcohol containing in principal from 18 to 30 carbon atoms is mixed with a colloidal, hydrophobic-reacting silicic acid at a ratio for alcohol:silicic acid of from 100:2 to 100:20, preferably from 100:3 to 100:10, and heated with agitation to temperatures between 100.degree. and 240.degree. C. for a time sufficient to give a homogeneous mixture, usually from one to five hours, preferably under an inert gas atmosphere. A homogeneous, liquid product is obtained upon subsequent cooling to room temperature. The practically silicone-free, antifoaming agent prepared by this method is particularly suitable for incorporation in washing and cleaning products by the usual finishing methods. Guerbet alcohols are used preferably as the branched-chain alcohols. The effectiveness of this antifoaming agent is comparable to that of known silicone-containing, antifoaming agents.